In many types of hydraulic turbines the various components are fabricated as individual units. This permits shop assembly in stages or even field assembly in stages. However, in the larger size of turbines wherein unitized construction is utilized to reduce cost and increase the strength of the components, difficulty has been experienced in installing the lower gate stem bushing so as to provide true alignment for the wicket gate stem or shaft. In the past, the bushings were installed in the shop in holes machined in a separate bottom, independent bottom ring or in the discharge ring. This operation requires a boring fixture or template to locate the holes accurately.
However, in the large sizes of turbines, the components are fabricated in sections and assembled in the field. Also, unitized construction is introduced to increase the structural strength of the machine and also to reduce the cost of manufacturing. Thus, unitized stay ring-discharge ring is assembled in the field and encased in the concrete structure prior to the other components. This, of course, creates problems, especially where a plurality of holes are to be provided which holes must be in alignment.
It is a general object of the present invention to provide a method and apparatus for aligning and installing wicket gate bushings in a unitized stay ring-discharge ring.
Yet another object of the present invention is to provide a method and apparatus for accomplishing the field alignment and installation of lower gate stem bushings in a unitized stay ring-discharge ring of a hydraulic turbine machine.
Still another object of the present invention is to provide a method and apparatus for the field alignment and installation of wicket gate stem bushings that do not require the provision and use of expensive boring fixtures or templates.
A further object of the present invention is to provide a method and apparatus which allows the utilization of unitized stay ring-discharge ring construction wherein the bearing holes for the stems of the wicket gates may be cut in the shop without the necessity of a fixture and the plurality of wicket gate bearings can be field installed with substantially perfect alignment.